Centrifuges



May 5, 1959 K. E. H. DQANIELSSON ETAL 2,885,145

CENTRIFUGES Filed Oqt. 15, 1957 :s Shee ts-Shet 1 INVENTORS KARL ERIKHARRY DAN/ELSSON JOHAN FOLKE S/GURD LUA; MAQK m,

A TTOR NE Y6 May 5, 1959 -K. E. H. DANIELSSON ET AL CENTRIFUGES FiledOct. [15. 1957 3 Sheets-Sheet 2 INVENTURS KARL ERIK HARRY DAN/ELSSO/Y y1959 E. H. DANlE LSSON ET AL v 2,885,145

CENTRIFUGES Filed Oct. 15, 1957 3 Sheets-Sheet 3 Fig. 8

INVENTUPS KARL ERIK HARRY DAN/ELSSUN JOHAN FULKE J/GURD LUNDMARKCENTRIFUGES Karl Erik Harry Danielsson and Johan Folke Sigurd Landmark,Orebro, Sweden, assignors to B 'Nyrnan Abn Aktiebolag, TyresmSweden, acompany of Sweden Application October 15, 1957, Serial No. 690,268Claims priority, application Sweden October 19, 1956 14 Claims. (Cl.233-26) curate determination of the relative quantity of the particlessuspended in the liquid.

Another object of the invention is to provide a centrifuge in whichsample tubes of extraordinary lengths can be subjected to centrifugalaction.

Still another object of the invention is to provide a centrifuge whichis small, inexpensive and handy in operation, and which does not involveany hazards to the personnel operating the same.

Further objects of the invention will appear from the followingdescription in which some embodiments of the invention have been setforth in detail with reference to the accompanying drawings.

Referring to the drawings:

Fig. l is an elevational cross-sectional view of a first embodiment ofthe centrifuge incorporating the present invention. Fig. 2 is a top planview of a tube holder forming part of said centrifuge. Fig. 3 is aperspective fractional view on a larger scale of said tube holder and asample tube held thereby. Fig. 4 shows a modification of a detail. Fig.5 is a cross-sectional view of a second embodiment, and Fig. 6 is asimilar view of a third embodiment of the tube holder. Fig. 7 is across-sectional view of ,a fourth embodiment of the head of thecentrifuge, and Fig. 8 is a top plan view of the same.

Referring to Fig. 1, the numeral 11 designates a base carrying anelectric motor 13 capable of running at a speed of 3000 revolutions perminute or more. Attached by means of a threaded knob 17 to the upper endof the vertical shaft of the motor is a head consisting of a holder inthe shape of a fiat circular disk 19 and a fiat covering disk 21. 23designates a protecting bowl surrounding the rotary parts.

The holder disk 19, the diameter of which is of the order of 6 inches,is preferably made of a transparent thermoplastic material. Moulded inits upper side is a groove 25 of a rectangular cross-section running oneor more turns around the centre of the disk and at an increasingdistance therefrom, thus having the configuration of a plane spiral. Thelength of the groove may be about inches. At its outer end the groove iswidened. Straight branch grooves 29, 31, 33 and 34 extend tangentiallyfrom the spiral groove and form different angles to the radialdirection. Four radial grooves 36 are formed in the the lower face ofthe disk.

The sample tubes pertaining to the centrifuge consist 2,885,145 PatentedMay 5, 1959 of a thin and flexible tube of a transparent or translucentplastic material, such as polyvinyl chloride, polyethylene or similar,cut in appropriate lengths, e.g. ,20 inches. The inner diameter of thetube is of the order of of an inch and the wall thickness is about A ofan inch. Such a tube can easily be cut by an ordinary pair of scissors.The tube can easily be closed by doubling up the tube end and tying thesame with a-cord or simply by tying a knot on the tube end itself.

The spiral groove 25 of the disk 19 is of such a size that a tube piece35 of the above-mentioned shape can be inserted therein, the knot 37being placed into the widened part 27 of the groove. Preferably thedepth of the groove corresponds closely to the outer diameter of thetube, and the width may be somewhat smaller than the diameter of thetube, whereby the tube is held by frictional engagement with the groovesides. When the cover 21 has been put on and the knob 17 screwed up, thetube is securely held and cannot be thrown out of the groove during thecentrifugation. The cover 21 is made of a transparent plastic material,such as acrylate, which makes it possible after stopping the centrifugebut without removing the tube from the holder to inspect and read offthe length of the column of heavier particles of the investigatedliquid, collected in the end of the tube. When desired, the part of thetube containing such a column of interest may be sheared off andsubjected to a further centrifugal action. In that case the tube piececut off is placed in any of the straight grooves 29, 31, 33 and 34forming angles to the radius of the disk,,or the disk is turned upsidedown and the tube piece is placed in one of the radial grooves 36. Whencentrifuging blood samples the red blood cells are collected to form acolumn at the outermost end of the tube, the

white blood cells which are not quite so heavy, form a short column atthe inner side thereof and the innermost greater part of the tube isfilled with the lighter, almost colourless blood plasma. The borders ofthe different columns are easily perceivable and if, for instance, it isdesired to further investigate the white blood cells they can easily beseparated by cutting off the corresponding part of the tube.

A number of samples can be treated by centrifugal action simultaneously,a corresponding number of holder disks 19 with tubes inserted in theirspiral grooves being piled on top of each other and commonly attached tothe shaft by the knob 17. An upper disk will then close the groove of alower disk and confine the flexible tube. If the branch grooves 29, 31,33 and 34 are dispensed with, a number of parallelly running spiralgrooves may be provided in one and the same disk face.

Fig. 4 shows a preferableprofile of the groove Which can be made by amilling cutter. The outer side is undercut and given a circularcross-section so as to suit the shape of the tube 25. The narrowentrance of the groove has a slightly smaller width than the diameter ofthe tube, and therefore the tube is safely retained in the groove afterhaving been forced through said entrance with a certain elasticdeformation. The tube is pressed against the groove side 39 also due toits elastic resistance to being curved. During the centrifugal actionthe tube is pressed still more forcefully against the groove side 39, sothat there is no risk for the tube being thrown out. Therefore, withsaid shape of the groove the cover disk 21 may be dispensed with.

Usually the spiral groove is of a uniform width except at its outer end.However, it may exceptionally be formed with narrow parts, where theflexible tube pressed down into the groove is more or less flattened, sothat its cross-sectional area is diminished. In this way a short columnof particles which is collected in said part of the tube is lengthenedwhich makes it easier to estimate the relative content of said particlesor to separate the same 7 by cutting off the tube. The same object canbe reached by manufacturing the tubewith narrow parts.

In the embodiment shown in Fig. 5 theholder consists of a central flatpart 41 and a conicalpart 43.. Cut out in the outerface of the conicalpart is a groove 45 having the configuration of afconical spiral withitscentre on the axis of rotation of the holder and having. across-section suitable to house the tube 35. A number of said holdersmay be piled and simultaneously attached to the motor shaft of thecentrifuge. The groove 45 is closed and the tube 35 is prevented frombeing thrown out, by the holder following nextin the upward direction.

In the embodiment shown in Fig. 6 the holder is made in the shape of abowl 4! having an inner conical surface tapcringdownwardly, in which agroove 49having the shape of a conical spiral is cut out. A tube placedin said groove is pressed down into the bottom ofthe groove by i i thecentrifugal forces and thereforethe groove may be t M thecentrifugation. The bowl has an inedge 51 for catching the'tube in caseit would come. loose anyway. Arranged at the upper and outermost end ofthe groove is a clamping device 52 by means of which the end of thecoiled tube loosely tucked down intothe groove is fastened, so that thetube cannot slide in its longitudinal direction. The clamping devicealso serves to close the tube end.

In the embodiment shown in Figs. 1 and a, there is attached to the shaftof the motor of the centrifuging a disk 50 having at its periphery anannular flange 53 with an inwardly directed edge. Vertical plates 55attached to the upper side of said disk form four radially directedcompartments, in each of which a cylindrical tube holder 57 can beplaced. One end of said holder is held by a pin 59 inserted into a borein the annular flange 53, and the other end is held by a washer 61 and awing nut 63 threaded upon the central shaft 15. The cylindrical surfaceof the holder 57 has a groove 65 in the shape of a square screw thread.When the flexible tube 35 is wound around the holder 57 and the holderclamped to the disk; 50, the tube forms a cylindrical spiral withitsaxislocated in an axial plane and at right angles to the axisofrotation. At the outer'end as well as at the inner end of the groovethere areprovided clamping devices 7 and 6, respectively, by means ofwhich the tube ends are fastened to the holder and closed during thecentrifugatiom" The holder 65 has a central bore 71, into which a pieceof the. flexible tube or an ordinary sample tube of glass can beinserted for being centrifuged.

The above-described embodiments are merly examples which may be modifiedin various respects without departing from the general inventive idea asset forth in the following claims.

We claim:

1. In a centrifuge, a head mounted for rotation about a vertical axis, aflexible sample tube, and means for defining a spiral configuration ofthe sample tube when associatedwith said head.'

2. In a centrifuge, a rotary head having a groove, a thin flexiblesample tube inserted in said groove, said groove being at least as wideas the diameter of the tube and having a longitudinal orifice of a widthsmaller than diameter of the tube, whereby passage of the tube throughsaid orifice requires elastic deformation of the tube.

3. In a centrifuge, a motor-driven vertical shaft, a horizontal circulardisk centrally attached to said shaft, said disk having a spiral-shapedgroove in its upper face for housing a flexible sample tube.

4. In a centrifuge, a motor driven vertical shaft, a circular diskcentrally attached to said shaft, said disk having a spiral groove inits flat face, a flexible sample tube located in said groove, and asecond disk bearing against said first-mentioned disk to confine saidtube in said groove.

5. A centrifuge as setforth in claim 4, in which said disks and saidtube are made of transparent material.

6. For use in a centrifuge, a circular disk havinga central aperture forattachment, a spiral groove in the flat face of said disk, said grooveencircling said central aperture and having a length greater than thediameter of the disk. t

7. A disk as set forth in claim 6, in which the cross section of thegroove is uniform over essentially the entire length of the groove, theoutermost part of the groove being widened.

8.-A disk as set forth inclaim 6, in which the cross section of thegroove is locally restricted.

9. A disk as set forth in claim 6, having a radially directed grooveinthe face opposite to the face having the spiral groove.

10. A disk as set forth in claim 6, having a straight groovetangentially joining the spiral groove.

11. A disk as set forth in claim 6, having a plurality of straightgrooves forming different angles to the radial direction.

12. A disk as set forth in claim 6, being made of a plastic transparentmaterial.

13. In a centrifuge, a head mounted for rotation about a vertical axis,said head comprising a conical tube holder having a groove forming aconicalspiral on the surface of said tube holder, and a flexible sampletube confined in said groove.

14. In a centrifuge, a head mounted for rotation about a vertical axis,a spiral groove in said head, and clamping means on said head forattaching and closing the end of a flexible sample tube inserted in saidgroove.

References Cited in the file of this patent UNITED STATES PATENTS2,783,938 Grcla Mar. 5, 1957

